Group-Based Prs Broadcast for Sidelink Positioning

1. A first wireless communication device in a wireless communication network, comprising: a wireless transceiver; one or more memories; and one or more processors coupled to the wireless transceiver and the one or more memories, wherein the one or more processors are configured to: send a first group formation message over a sidelink channel via the wireless transceiver to form a positioning group comprising a plurality of wireless communication devices including the first wireless communication device, the first group formation message being broadcast during a group phase in a time domain, the group phase comprising at least an initiator sub-phase within which one or more initiator devices can send respective group formation messages and a responder sub-phase within which one or more responder devices can send respective other group formation messages; and communicate positioning reference signals (PRSs) between the plurality of wireless communication devices in the positioning group over the sidelink channel via the wireless transceiver.

2. The first wireless communication device of claim 1, wherein: at least one of the one or more initiator devices or the one or more responder devices comprises an anchor device or a non-anchor device, the anchor device comprising a respective known location based on a location accuracy, and the non-anchor device comprising a respective unknown location based on the location accuracy.

3. The first wireless communication device of claim 2, wherein the one or more processors are further configured to: send the first group formation message during the initiator sub-phase based on the first wireless communication device being the anchor device to identify the first wireless communication device as an initiator device for the positioning group.

4. The first wireless communication device of claim 3, wherein the one or more processors are further configured to: receive a second group formation message during the initiator sub-phase from a second wireless communication device.

5. The first wireless communication device of claim 4, wherein the one or more processors are further configured to: exclude the second wireless communication device from the positioning group.

6. The first wireless communication device of claim 3, wherein the one or more processors are further configured to: receive a third group formation message from a third wireless communication device within the responder sub-phase, wherein the third wireless communication device is one of the one or more responder devices; and include the third wireless communication device in the positioning group.

7. The first wireless communication device of claim 6, wherein the third wireless communication device is the non-anchor device or another anchor device.

8. The first wireless communication device of claim 6, wherein each of a plurality of group formation messages comprising the first group formation message and the third group formation message comprise: initiator information indicating whether a transmitting device of a respective group formation message of the plurality of group formation messages is the initiator device of the positioning group, anchor information indicating whether the transmitting device is the anchor device, power information indicating whether the transmitting device is power limited, and a group identity (ID) identifying the transmitting device within the positioning group.

9. The first wireless communication device of claim 8, wherein the group ID comprises a random number.

10. The first wireless communication device of claim 8, wherein the third group formation message further comprises: an initiator ID of the initiator device of the positioning group, and respective responder IDs of each of the one or more responder devices that send the respective group formation messages within the responder sub-phase prior to the third group formation message.

11. The first wireless communication device of claim 10, wherein the initiator ID is based on the group ID of the initiator device and each of the responder IDs are based on the respective group IDs of each of the one or more responder devices.

12. The first wireless communication device of claim 10, wherein the one or more processors are further configured to: send a group association message identifying the plurality of wireless communication devices within the positioning group and an order of the plurality of wireless communication devices in the positioning group beginning with the initiator device.

13. The first wireless communication device of claim 12, wherein: each of the plurality of group formation messages comprises a basic field value produced as a composite of the initiator information, the anchor information, the power information, and the group ID, and the order of the plurality of wireless communication devices is listed in the group association message in decreasing order of the respective basic field values associated with each of the plurality of wireless communication devices.

14. The first wireless communication device of claim 13, wherein the group association message comprises the respective responder IDs of each of the plurality of wireless communication devices in the positioning group.

15. The first wireless communication device of claim 3, wherein the one or more processors are further configured to: reserve the sidelink channel for a channel occupancy time (CoT) for transmission of the PRSs within a PRS phase subsequent in time to the group phase.

16. The first wireless communication device of claim 15, wherein the one or more processors are further configured to: determine respective transmission timing of each of the PRSs within the CoT from the order of the plurality of wireless communication devices.

17. The first wireless communication device of claim 2, wherein the one or more processors are further configured to: send the first group formation message during the responder sub-phase based on the first wireless communication device being a responder device of the one or more responder devices for the positioning group.

18. A method of wireless communication, the method comprising, at a first wireless communication device: sending a first group formation message over a sidelink channel to form a positioning group comprising a plurality of wireless communication devices including the first wireless communication device, the first group formation message being broadcast during a group phase in a time domain, the group phase comprising at least an initiator sub-phase within which one or more initiator devices can send respective group formation messages and a responder sub-phase within which one or more responder devices can send respective other group formation messages; and communicating positioning reference signals (PRSs) between the plurality of wireless communication devices in the positioning group over the sidelink channel.

19. The method of claim 18, wherein: at least one of the one or more initiator devices or the one or more responder devices comprises an anchor device or a non-anchor device, the anchor device comprising a respective known location based on a location accuracy, and the non-anchor device comprising a respective unknown location based on the location accuracy.

20. The method of claim 19, further comprising: sending the first group formation message during the initiator sub-phase based on the first wireless communication device being the anchor device to identify the first wireless communication device as an initiator device for the positioning group.

21. The method of claim 20, further comprising: receiving a second group formation message during the initiator sub-phase from a second wireless communication device.

22. The method of claim 21, further comprising: excluding the second wireless communication device from the positioning group.

23. A first wireless communication device in a wireless communication network, comprising: means for sending a first group formation message over a sidelink channel to form a positioning group comprising a plurality of wireless communication devices including the first wireless communication device, the first group formation message being broadcast during a group phase in a time domain, the group phase comprising at least an initiator sub-phase within which one or more initiator devices can send respective group formation messages and a responder sub-phase within which one or more responder devices can send respective other group formation messages; and means for communicating positioning reference signals (PRSs) between the plurality of wireless communication devices in the positioning group over the sidelink channel.

24. The first wireless communication device of claim 23, wherein: at least one of the one or more initiator devices or the one or more responder devices comprises an anchor device or a non-anchor device, the anchor device comprising a respective known location based on a location accuracy, and the non-anchor device comprising a respective unknown location based on the location accuracy.

25. The first wireless communication device of claim 24, further comprising: means for sending the first group formation message during the initiator sub-phase based on the first wireless communication device being the anchor device to identify the first wireless communication device as an initiator device for the positioning group.

26. The first wireless communication device of claim 25, further comprising: means for receiving a second group formation message during the initiator sub-phase from a second wireless communication device.

27. The first wireless communication device of claim 25, further comprising: means for excluding the second wireless communication device from the positioning group.

28. A non-transitory computer-readable medium having stored therein instructions executable by one or more processors of a first wireless communication device to cause the first wireless communication device to: send a first group formation message over a sidelink channel via the wireless transceiver to form a positioning group comprising a plurality of wireless communication devices including the first wireless communication device, the first group formation message being broadcast during a group phase in a time domain, the group phase comprising at least an initiator sub-phase within which one or more initiator devices can send respective group formation messages and a responder sub-phase within which one or more responder devices can send respective other group formation messages; and communicate positioning reference signals (PRSs) between the plurality of wireless communication devices in the positioning group over the sidelink channel via the wireless transceiver.

29. The non-transitory computer-readable medium of claim 28, wherein: at least one of the one or more initiator devices or the one or more responder devices comprises an anchor device or a non-anchor device, the anchor device comprising a respective known location based on a location accuracy, and the non-anchor device comprising a respective unknown location based on the location accuracy.